Arkansas Nuclear 1 - Status & History

Comprehensive reactor performance metrics, cycle analysis, and historical outage data.
Data refreshed 6.4h ago Rx Status: Sep 8, 2026 at 5:21 AM (M-F)

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Reactor Status Timeline

Online NRC data, Mon to Fri ? Actual daily reactor status from NRC reports (Mon to Fri) and the current state. What is coming -- the utility's published Scheduled outage and NukeWorker's model Projection -- is part of a subscription. Colored by status. How far ahead you can see depends on your plan.
Oct2025NovDecJan2026FebMarAprMayJunJulAugSepOnline: Sep 8, 2025 to Sep 16, 2025Coastdown: Sep 17, 2025 to Sep 24, 2025Scram: Sep 25, 2025 to Sep 28, 2025Coastdown: Sep 29, 2025 to Oct 1, 2025Power Ascension: Oct 2, 2025 to Oct 10, 2025Refueling Outage (1R32): Oct 11, 2025 to Nov 13, 20251R32Power Ascension: Nov 14, 2025 to Nov 17, 2025Online: Nov 18, 2025 to Sep 8, 2026Scram (reactor trip): Sep 24, 2025Today
OnlineCoastdownPower AscensionRefueling OutageScram⚡Scram (reactor trip)
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Composite Operational Excellence Score (0-100) — average percentile rank across 7 dimensions in three sub-scores: Reliability (capacity factor, forced outage days, B2B avg streak), Efficiency (fuel utilization, refuel duration), and Discipline (startup duration, scram count). 5-year window. Higher = more operationally excellent. Click to see the full breakdown.
   
Excellence
ranked of 93
Subscribers
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Days of continuous operation since the last outage ended (Started 2025-11-13). Clean run (no forced outages since last refueling).
299
Current Run
days ✔
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Longest recorded period of continuous operation between outages (2010-04-26 to 2011-10-17).
539
Record Run
days
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Breaker-to-Breaker runs — continuous operation exceeding the cycle-adjusted threshold set for this unit with no trips to 0% power.
6
B2B Runs
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Lifetime capacity factor: average power level across all recorded days (100% = always at full power).
88.5%
Capacity Factor
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Net electricity actually generated over the most recent 12 months reported by the U.S. EIA (Form EIA-923), summed across every unit at this plant. Authoritative actuals, not an estimate.
14.07 TWh
Net Generation
EIA-923 · 12 mo to 2026-06 · plant total
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Total number of scheduled refueling outages detected in the historical data.
18
Outages
since 1999
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Average time from first power generation (>0%) to sustained full power (≥95% for 2+ days) across the last 3 scheduled outages. Click to compare against the fleet on the Operator Efficiency Leaderboard.
16.3
Avg Startup
days (last 3)
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Average fuel utilization — percent of the designed fuel cycle that this unit consumes before refueling, derived from the historical burn-down trajectory. Higher = more efficient operator (refuels with less margin remaining; closer to coastdown). Computed as 100% minus the unit's average refuel-point fuel %, using the last 3 years where available, otherwise lifetime average. Click to compare against the fleet on the Operator Efficiency Leaderboard.
96.8%
Fuel Utilization
3yr avg
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NukeWorker's Operational Excellence Score is a composite 0–100 ranking of every active US nuclear unit across 7 measured performance metrics, grouped into three sub-scores:
• Reliability — capacity factor, forced outage days, B2B avg streak
• Efficiency — fuel utilization, refuel duration
• Discipline — startup duration, scram count
Each unit's metric is converted to a percentile across the active fleet. Sub-score = average of its components; composite = average of the three sub-scores. Use the time-window toggle below to switch between 3yr / 5yr / lifetime.
Time window — change how far back we look
5-yr trend: 2021: 14/100 (#88/93)2022: 14/100 (#88/92)2023: 19/100 (#87/92)2024: 38/100 (#67/92)2025: 29/100 (#79/92)2026: 35/100 (#71/93) ↑ +5.7 pts vs 2025
Compare Arkansas Nuclear 1 head-to-head with up to 3 other units. Compare now
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Duration of each outage in days, shown chronologically. Green bars are scheduled refueling outages, red bars are forced/unscheduled. The orange dashed line marks the average duration. Extended outages (>180 days) and D&D periods are excluded.

Outage Duration Trend

Arkansas Nuclear 1 has 47 outages plotted here, averaging 21 days each. The most recent, in Oct 2025, was a scheduled refueling outage lasting 34 days.
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Time in days from first power generation (>0%) to sustained full power (≥95% for 2+ consecutive days) after each scheduled refueling outage. The dashed line marks the average. Includes startup testing holds and power dips.

Startup Duration Trend

After a refueling outage, Arkansas Nuclear 1 takes about 3 days to climb from first power back to full power. That average is drawn from 18 startups on record, and the most recent took 4 days.
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Estimated fuel remaining in the current cycle, expressed as a percentage of the unit's typical cycle. Starts at 100% when the unit returns to power post-refuel and drops as full-power-days are burned. Days at reduced power burn fuel proportionally — so a unit with significant downtime (high burn deficit) drops slower and ends up with MORE fuel left than its calendar position would suggest. Coastdown threshold around 15%. Toggle to overlay past cycles on a normalized "days into cycle" axis to see how aggressively this unit historically burns down before refuel.

Fuel Burn Down Cycle since Nov 14, 2025

41.7% remaining 1.3 FPD margin
Arkansas Nuclear 1 has an estimated 41.7% of its fuel left. Across its last 17 cycles, it has refueled with an average of 4.0% remaining.
Avg refuel: 4.0% Avg refuel (3yr): 3.2% Deepest burn: 0.0% (2001-04 → 2002-10) Most margin: 14.3% (2016-12 → 2018-03)
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Monthly capacity factor with outage events overlaid as red bands. Green bars show average power level per month. Toggle to Daily view for raw daily data.

Power History

Over its operating life, Arkansas Nuclear 1 has run at about 88.5% of its rated capacity. Across the last 12 reported months it averaged 89.3%. On the chart, flat stretches near the top are full-power running and drops to zero are outages.
This table logs every recorded outage for Arkansas Nuclear 1, 47 in all since 1999. Of those, 18 were scheduled refueling outages and 29 were unplanned or forced. The typical outage lasted about 21 days. Where the Scheduled column shows (Model), the date is a NukeWorker projection because the utility had not published one.
Type ⇅ Actual Start ⇅ Actual End ⇅ Duration ⇅ Days Online ⇅ Scheduled Delta
Scheduled 1R32
2025-10-11 2025-11-13 34 13d 2025-10-08 +3d
Scram # 57949
2025-09-25 2025-09-28 4 290d - -
Unscheduled
2024-12-05 2024-12-09 5 200d - -
Scheduled 1R31
2024-04-27 2024-05-19 23 144d 2024-04-26 +1d
Unscheduled
2023-12-04 2023-12-05 2 291d - -
Scram # 56351
2023-02-15 2023-02-16 2 48d - -
Unscheduled
2022-11-25 2022-12-29 35 2d - -
Scheduled 1R30
2022-10-08 2022-11-23 47 311d 2022-10-08 0d
Scram # 55614
2021-11-30 2021-12-01 2 206d - -
Scheduled 1R29
2021-04-10 2021-05-08 29 24d 2021-04-10 0d
Scram # 55138
2021-03-15 2021-03-17 3 483d - -
Scheduled 1R28
2019-10-06 2019-11-18 44 289d 2019-09-16 +20d
Scram # 53793
2018-12-19 2018-12-21 3 176d - -
Unscheduled
2018-06-23 2018-06-26 4 5d - -
Scram # 53459
2018-06-17 2018-06-18 2 2d - -
Unscheduled
2018-06-13 2018-06-15 3 24d - -
Scram # 53404
2018-05-17 2018-05-20 4 2d - -
Scheduled 1R27
2018-03-24 2018-05-15 53 311d 2018-03-24 0d
Scram # 52710
2017-04-27 2017-05-17 21 136d - -
Scheduled 1R26SGR/Major
2016-09-24 2016-12-12 80 282d 2016-09-18 +6d
Scram # 51607
2015-12-16 2015-12-17 2 290d - -
Scheduled 1R25
2015-01-26 2015-03-01 35 528d 2015-01-25 +1d
Unscheduled
2013-08-15 2013-08-16 2 10d - -
Scheduled 1R24SGR/Major
2013-03-25 2013-08-05 134 491d 2013-03-24 +1d
Scheduled 1R23
2011-10-17 2011-11-20 35 539d 2011-10-16 +1d
Unscheduled
2010-04-19 2010-04-26 8 2d - -
Scheduled 1R22
2010-03-22 2010-04-17 27 406d 2010-04-20 -29d
Unscheduled
2009-02-08 2009-02-09 2 2d - -
Unscheduled
2009-02-06 2009-02-06 1 45d - -
Unscheduled
2008-12-21 2008-12-23 3 10d - -
Scheduled 1R21
2008-10-27 2008-12-11 46 533d 2008-10-26 +1d
Scheduled 1R20
2007-04-23 2007-05-13 21 480d 2007-04-22 +1d
Unscheduled
2005-12-27 2005-12-29 3 6d - -
Scheduled 1R19SGR/Major
2005-10-05 2005-12-21 78 473d 2005-10-04 +1d
Unscheduled
2004-06-12 2004-06-19 8 31d - -
Scheduled 1R18
2004-04-21 2004-05-12 22 133d 2004-04-20 +1d
Unscheduled
2003-11-16 2003-12-10 25 78d - -
Unscheduled
2003-08-30 2003-08-30 1 291d - -
Scheduled 1R17
2002-10-05 2002-11-12 39 437d 2002-10-05 0d
Unscheduled
2001-07-25 2001-07-25 1 108d - -
Scheduled 1R16
2001-03-17 2001-04-08 23 70d 2001-03-17 0d
Unscheduled
2001-01-06 2001-01-06 1 298d - -
Unscheduled
2000-03-14 2000-03-14 1 2d - -
Unscheduled
2000-02-05 2000-03-12 37 25d - -
Unscheduled
2000-01-08 2000-01-11 4 91d - -
Scheduled 1R15
1999-09-11 1999-10-09 29 249d 1999-09-11 0d
Unscheduled
1999-01-01 1999-01-05 5 - - -
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